diff options
Diffstat (limited to 'net/ipv4/netfilter/ip_nat_amanda.c')
-rw-r--r-- | net/ipv4/netfilter/ip_nat_amanda.c | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ip_nat_amanda.c b/net/ipv4/netfilter/ip_nat_amanda.c new file mode 100644 index 00000000000..da1f412583e --- /dev/null +++ b/net/ipv4/netfilter/ip_nat_amanda.c @@ -0,0 +1,88 @@ +/* Amanda extension for TCP NAT alteration. + * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca> + * based on a copy of HW's ip_nat_irc.c as well as other modules + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + * Module load syntax: + * insmod ip_nat_amanda.o + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/netfilter.h> +#include <linux/skbuff.h> +#include <linux/ip.h> +#include <linux/udp.h> +#include <net/tcp.h> +#include <net/udp.h> + +#include <linux/netfilter_ipv4.h> +#include <linux/netfilter_ipv4/ip_nat.h> +#include <linux/netfilter_ipv4/ip_nat_helper.h> +#include <linux/netfilter_ipv4/ip_conntrack_helper.h> +#include <linux/netfilter_ipv4/ip_conntrack_amanda.h> + + +MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); +MODULE_DESCRIPTION("Amanda NAT helper"); +MODULE_LICENSE("GPL"); + +static unsigned int help(struct sk_buff **pskb, + enum ip_conntrack_info ctinfo, + unsigned int matchoff, + unsigned int matchlen, + struct ip_conntrack_expect *exp) +{ + char buffer[sizeof("65535")]; + u_int16_t port; + unsigned int ret; + + /* Connection comes from client. */ + exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; + exp->dir = IP_CT_DIR_ORIGINAL; + + /* When you see the packet, we need to NAT it the same as the + * this one (ie. same IP: it will be TCP and master is UDP). */ + exp->expectfn = ip_nat_follow_master; + + /* Try to get same port: if not, try to change it. */ + for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) { + exp->tuple.dst.u.tcp.port = htons(port); + if (ip_conntrack_expect_related(exp) == 0) + break; + } + + if (port == 0) { + ip_conntrack_expect_free(exp); + return NF_DROP; + } + + sprintf(buffer, "%u", port); + ret = ip_nat_mangle_udp_packet(pskb, exp->master, ctinfo, + matchoff, matchlen, + buffer, strlen(buffer)); + if (ret != NF_ACCEPT) + ip_conntrack_unexpect_related(exp); + return ret; +} + +static void __exit fini(void) +{ + ip_nat_amanda_hook = NULL; + /* Make sure noone calls it, meanwhile. */ + synchronize_net(); +} + +static int __init init(void) +{ + BUG_ON(ip_nat_amanda_hook); + ip_nat_amanda_hook = help; + return 0; +} + +module_init(init); +module_exit(fini); |